A buzzing light switch could mean the fixture is wearing out, causing an arc of electricity behind the wall plate. If this is the case, the potential for an electrical fire may exist.
According to the experts at This Old House, buzzing light fixtures are more common in dimmer switches. Sometimes, the repair is simple and may just involve replacing a light bulb or lowering the wattage.
An electrician is the right person to call with questions regarding electrical outlets or fixtures around the home. Hiring an electrician can cost anywhere from $30 to $70 per hour or more. According to homeadvisor.com, homeowners can save money by paying an electrician a per-job rate rather than an hourly rate.